Display skips swapping if overlays draw the damage

cc/output/gl_renderer.cc

 // Copyright 2010 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "cc/output/gl_renderer.h"
 
 #include <algorithm>
 #include <limits>
 #include <set>
 #include <string>
@@ skipping 2589 matching lines @@
 
   TRACE_EVENT0("cc,benchmark", "GLRenderer::SwapBuffers");
   // We're done! Time to swapbuffers!
 
   gfx::Size surface_size = output_surface_->SurfaceSize();
 
   CompositorFrame compositor_frame;
   compositor_frame.metadata = metadata;
   compositor_frame.gl_frame_data = make_scoped_ptr(new GLFrameData);
   compositor_frame.gl_frame_data->size = surface_size;
-  if (capabilities_.using_partial_swap) {
-    // If supported, we can save significant bandwidth by only swapping the
-    // damaged/scissored region (clamped to the viewport).
-    swap_buffer_rect_.Intersect(gfx::Rect(surface_size));
-    int flipped_y_pos_of_rect_bottom = surface_size.height() -
-                                       swap_buffer_rect_.y() -
-                                       swap_buffer_rect_.height();
-    compositor_frame.gl_frame_data->sub_buffer_rect =
-        gfx::Rect(swap_buffer_rect_.x(),
-                  FlippedRootFramebuffer() ? flipped_y_pos_of_rect_bottom
-                                           : swap_buffer_rect_.y(),
-                  swap_buffer_rect_.width(),
-                  swap_buffer_rect_.height());
-  } else {
-    compositor_frame.gl_frame_data->sub_buffer_rect =
-        gfx::Rect(output_surface_->SurfaceSize());
-  }
+  // If supported, we can save significant bandwidth by only swapping the
+  // damaged/scissored region (clamped to the viewport). The surface can
+  // choose whether to do a full swap or partial swap.

[piman, 2015/11/19 21:22:04]

If we do that we need to fix all the OutputSurface implementations. See e.g.
GpuBrowserCompositorOutputSurface::SwapBuffers

+  swap_buffer_rect_.Intersect(gfx::Rect(surface_size));
+  int flipped_y_pos_of_rect_bottom = surface_size.height() -
+                                     swap_buffer_rect_.y() -
+                                     swap_buffer_rect_.height();
+  compositor_frame.gl_frame_data->sub_buffer_rect =
+      gfx::Rect(swap_buffer_rect_.x(),
+                FlippedRootFramebuffer() ? flipped_y_pos_of_rect_bottom
+                                         : swap_buffer_rect_.y(),
+                swap_buffer_rect_.width(), swap_buffer_rect_.height());
   output_surface_->SwapBuffers(&compositor_frame);
 
   // We always hold onto resources for an extra frame, to make sure we don't
   // update the buffer while it's being scanned out.
   previous_swap_overlay_resources_.clear();
   previous_swap_overlay_resources_.swap(in_use_overlay_resources_);
 
   in_use_overlay_resources_.swap(pending_overlay_resources_);
 
   swap_buffer_rect_ = gfx::Rect();
@@ skipping 934 matching lines @@
       texture_id = pending_overlay_resources_.back()->texture_id();
     }
 
     context_support_->ScheduleOverlayPlane(
         overlay.plane_z_order, overlay.transform, texture_id,
         ToNearestRect(overlay.display_rect), overlay.uv_rect);
   }
 }
 
 }  // namespace cc